Why is Winston's betrayal of Julia such a key point in 1984?

Whenis caught by the
government, he is told that there are three stages to his "reintegration": learning,
understanding, and acceptance.  Winston doesn't betrayuntil the last stage and when he yells for
the torturers to, "Do it to Julia! Not me!", he has capitulated and accepted Big
Brother.  The acceptance of Big Brother is essential to the government because it means that
Winston no longer has free will; he is nothing more than a pawn of the government.  Winston had
thought he was strong and that he loved Julia.  The government does not want any of the people
to love anyone more than they love Big Brother and the government because that means that the
individual might favor the one loved over the government. By betraying Julia, Winston shows that
he loves the government, and Big Brother, more than anyone else.